1. Field of the Invention
The present invention relates to an apparatus for reading radiation image information from a temporary storage medium by measuring intensities of accelerated phosphorescence while projecting exciting light onto the temporary storage medium. The temporary storage medium receives radiation, e.g., an X-ray that has been transmitted through an object under examination.
2. DESCRIPTION OF THE PRIOR ART
The accelerated phosphorescence is known as a luminescent phenomenon. That is, the temporary storage medium such as visual light-stimulable phosphor, infrared-stimulable phosphor, or thermoluminescent material stores an incident pattern of energy radiation in its lattice defect during the radiation exposure, and after the radiation exposure, the storage medium illuminates the accelerated phosphorescence whose intensities are directly proportional to the energy stored therein while being exposed with the exciting light.
Such an accelerated phosphorescence storage medium is, for example, formed in a sheet. An X-ray is projected to the storage sheet so as to temporarily store in its lattice defect an image representative of an incident radiation intensity pattern. Thereafter, this storage sheet is scanned by the exciting light such as laser light to release the stored energy as intensity modulated light. The scanned light is detected by an appropriate detector so as to be converted into an electrical signal modulated in accordance with the intensity modulation of the incident light. The electrical signal is further processed to display the radiation image of the object on the TV monitor, or to record it on the photographic film. Such a typical example of use of the accelerated phosphorescence storage medium is known, for instance, from U.S. Pat. No. No. 3,859,527 to Luckey, issued on Jan. 7, 1975.
In the radiation image reading apparatus, it is desirable to realize a wider dynamic range and a faster reading rate.
It is therefore an object of the present invention to provide an apparatus for reading radiation image information by simultaneously scanning one line of a radiation image with the exciting light.
Another object of the present invention is to provide an apparatus for reading radiation image information by repeatedly scanning the same line of the radiation image with the exciting light, the intensity level of which is changed every scanning period.